Quick release aerator

ABSTRACT

A quick release aerator is provided for discharging intermittent bursts of pressurized air into a storage container to implement material flow. The unit includes a piston and valve assembly disposed internal to a pressure tank. The assembly features one or more vent ports defined through the sidewalls of a cylinder to allow the passage of pressurized air from the tank to an outlet orifice. The total area of the vent ports equals or exceeds the area of the exhaust port, thereby maximizing the effect of the burst of pressurized air.

BACKGROUND OF THE INVENTION

The present invention deals with an improved construction of an internalvalve quick release air cannon. Devices of this type are utilized toaccumulate pressurized air and, upon receipt of a controlled signal, torapidly discharge a burst of pressurized air into the interior of astorage hopper. The intermittent bursts of pressurized air promote theflowability of material in the hopper preventing hang up and bridging ofmaterial internal to the hopper. Typical prior art arrangements areshown in U.S. Pat. Nos. 3,942,684 and 4,051,982 issued to applicant.These patents illustrate "external valve" arrangements in which thepiston and valve are located outside of the tank. One example of an"internal valve" arrangement is shown in U.S. Pat. No. 3,788,527 ofapplicant. This aerator, like the present arrangement, has the pistonand valve assembly disposed inside the pressure tank.

SUMMARY OF THE INVENTION

To maximize the effectiveness of the bursts of pressurized air deliveredfrom the tank to the hopper, it is necessary to optimize the flow of airwhen the piston unseats from the seal. In prior art arrangements, thearea of the flow passage from the pressure tank to the outlet of theunit was always the limiting factor since this area was always less thanthe area of the exhaust port. Depending upon the relative difference inareas, this restriction to flow presented either substantial or moderateimpedance to maximizing the force generated by the air bursts directedinto the hopper. Flow was restricted by the nozzle effect of the flowpassage and by sonic velocity. The present invention allows optimizationof the force generated by such bursts to be achieved by sizing the areaof the vent ports which define the passage from the tank to the outletport to be equal to or greater than the area of the outlet port itself.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view partially broken away showing the aerator of thepresent invention with the piston in its raised or unsealed condition.

FIG. 2 is a side view partially broken away of the piston and valvearrangement showing the piston in its downward or sealed position.

FIG. 3 is a side view illustrating only the cylinder of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a quick release air discharge unit 10 which isadapted to be connected to a storage vessel to discharge intermittentbursts of pressurized air thereby promoting the flowability of materialin the hopper. The aerator or air discharge unit includes a pressuretank 11, shown in FIG. 1, as being ellipsoidal in configuration. Theellipsoidal shape of the pressure container 11 provides a number ofbenefits including providing for a straighter, less interrupted flow ofpressurized air than in typical prior art embodiments. It also resultsin a less costly installation than those used in the past.

Disposed within the pressure container 11 is a piston and valve assembly12 consisting of a cylinder 13, a piston 15, and a seal 16. The piston15 is slidably disposed within the cylinder 13 and normally assumes theclosed position as illustrated in FIG. 2. For purposes of reducing themass of the piston, it is desirable to construct it of lightweightmaterial, for example, plastic or aluminum or rubber. The cylinderdefines a fluid inlet 17 disposed at one end thereof.

A fluid inlet port 18, shown in the form of a fluid coupling orconnector, is disposed in a wall of the tank 11. The connector 18 isadapted to be connected to any suitable source of pressurized fluid,such as, for example, a compressor, not shown. A conduit 20 connectsfluid inlet port 18 and the inlet 17 of cylinder 13. If the conduit 20is formed of rubber or some other material subject to collapse underpressure, it has been determined advisable to insert a spring, notshown, in the interior thereof to prevent collapse from exposure to thepressure generated in the tank 11. A connector 21 couples the conduit 20to the inlet 17 of cylinder 13.

An orifice 22 is defined in the sidewall of the cylinder 13 adjacent theend on which the inlet 17 is disposed. This orifice is relatively smallin size and allows a restricted flow of air from the pressure source tothe tank when the piston is in the position illustrated in FIG. 2. Alsoformed in the wall of cylinder 13 are one or more vent ports 23A, 23B,23C, and 23D. Ports 23A and 3B are shown in FIG. 1, and ports 23C and23D are illustrated in FIG. 3. The exact number, dimensions, andconfiguration of the vent ports 23 can be determined according torelevant design characteristics of the aerator so long as the relativerelationship between the vent port area and that of the outlet port isconsistent with the principles of the present invention, namely, thatthe total area of the vent ports be equal to or greater than the area ofthe exhaust port.

The piston 15 defines, toward its lower face, an inwardly slopingchamfer 19, the purpose of which will be described later. The piston 15defines a bore 25 in its central portion extending from the upper face26 of the piston to a point below the center of the piston, but short ofthe lower face 27 of the piston. The bore 25 provides a recess in whicha spring 28 is located. The upper end of spring 28 abuts against theinside upper wall of the cylinder 13 so as to bias the piston 15 intoits downward or sealing position as shown in FIG. 2. The piston 15further defines a groove 30 around its upper perimeter within which isdisposed an O-ring 31 for the purpose of restricting the flow of airbetween the sidewall of piston 15 and cylinder 13.

The cylinder housing 13 includes an outwardly disposed leg 32 which isadapted to be positioned within a corresponding outwardly extending leg33 in flange 35. The flange 35 is secured within an opening defined inthe wall of the tank 11. A mating flange 36 carries exhaust pipe 37which communicates pressurized air from the tank to the hopper. Theflange 36 is adapted to be connected to the flange 35 by means of bolts38 secured into threaded recesses 40 formed in the flange 35. Such anarrangement assures easy removal of the piston and valve assembly andthe seal from the tank when servicing or replacement is indicated.

As shown in FIGS. 1 and 2, the seal member 16 is secured between flange35 and housing 13 and lies within a recess formed in flange 35. The seal16 consists of an annular base member 41 and a chamfered face section 42which includes an upper end 43 and a lower end 45. An annular exhaustport 44 is defined by the lower end 45 of the chamfered face. It is thisexhaust port which must have an area equal to or less than the totalarea of the vent ports 23. In order to insure a quick release actionwhen the piston is depressurized, it is desirable to maximize thedifferential area of the piston which is exposed to the pressurizedfluid in the tank. Accordingly, the chamfer 19 is designed with a slopewhich is greater than the slope of the chamfer 42. In a preferredembodiment, which has functioned in a satisfactory manner, the chamfer19 is cut at an angle of 55°, while the chamfer 42 is cut at an angle of48°. The difference of 7° results in a greater differential area of thepiston 15 being exposed to the pressure in the tank 11 as shown in FIG.2. The length of the chamfered face 19 is greater than the length of thechamfer face section 42 which assists the snap action release. Theactual point at which the piston contacts the seal is located as fardown the face section 42 as possible. The seal member 16 defines anannular groove 46 in its outer perimeter in which an O-ring 47 ispositioned.

A pressure relief valve 48 of standard design is shown disposed in thewall of the pressure tank 11 to prevent the accumulation of air beyondthe design parameters of the tank.

The operation of the present invention is as follows. Prior topressurization of the unit, the piston 15 assumes the positionillustrated in FIG. 2. The force of gravity, in combination with theforce exerted by spring 28, resiliently biases the piston 15 downwardlyso that a portion of the chamfered face 19 of the piston lies against aportion of the chamfered face section 42 of the seal. This position ofthe elements blocks any fluid flow between the pressure source and theexhaust pipe 37. Once the unit is pressurized, the pressure sourcedelivers pressurized fluid through coupling 18, conduit 20, andconnection 21 through the inlet 17 of the cylinder. The pressurizedfluid passes through the restricted orifice 22 into the tank 11 and isallowed to accumulate in the tank with the pressure increasing. In mostinstallations, the pressurized fluid is air, but for certainapplications, other fluids may be preferred. The pressure within thecontainer acts on the top face of the piston 15 supplementing the forceof the spring 28 and urging the piston downwardly against the seal 16,thus preventing the flow of air from the tank 11 through the exhaust 37.

This condition continues until such time as the pressure in thecontainer reaches the pressure determined to be appropriate fordischarge. Any of a number of mechanisms are known in the art to triggerdischarge including timers or a variety of pressure responsive flowcontrol devices. Once it has been determined to release a burst of airfrom the tank, the inlet 18 is depressurized and the inlet 17 of thecylinder 13 is placed in communication with atmosphere. This releasesthe force of the pressurized air previously acting on top of the pistonto urge it downwardly. Simultaneously, the pressurized air in the tank11 acting on the exposed portion of chamfer face 19 exerts a force onthe piston in an upward direction of a magnitude far in excess of thedownward force exerted by the spring 28. The piston 15 immediately snapsupwardly to the position shown in FIG. 1 thereby unsealing the outletport 44 defined by the lower end 45 of the chamfer face section 42.Since the total area of the vent ports 23 is equal to or greater thanthe area of the exhaust port, pressurized air rushes, without reductionin velocity or volume, through the vent ports 23, the exhaust port 44,and the exhaust tube 37 into the silo or hopper to which the airdischarge unit is connected. The relative relationship between the totalarea of the vent ports 23 being equal to or greater than the area of theoutlet port 44 results in an optimum force generated by the burst of airdischarged into the container, the optimum force being the shortestpressure pulse.

Various features of the invention have been particularly shown anddescribed in connection with the illustrated embodiments of theinvention, however, it must be understood that these particulararrangements merely illustrate and that the invention is to be given itsfullest interpretation within the terms of the appended claims.

What is claimed is:
 1. A quick release air discharge unit adapted to beconnected to a storage vessel for facilitating the flow of materialsincluding a pressure tank, a piston and valve assembly disposed withinsaid pressure tank consisting of a cylinder defining a fluid inlet atone end and an outlet at the other end, one or more vent ports definedin the wall of said cylinder adjacent said cylinder outlet adapted toallow the passage of air from said tank to said outlet, said vent portshaving a defined area, a piston slidably disposed within said cylinderadapted to assume either a first or second position, an orifice definedin the wall of said cylinder adjacent said inlet to allow restrictedfluid flow from said cylinder to said tank when said piston is in saidfirst position, a seal member adjacent the outlet end of said cylinder,an exhaust port defiing a cross-sectional area less than or equal tosaid defined area of said vent ports for communicating pressurized airfrom said vent ports to said storage vessel, a fluid inlet port definedin a wall of said tank adapted to be connected to a source of fluidpressure, a fluid conduit connected between said fluid inlet port andsaid cylinder inlet, said unit operative such that said piston isnormally biased to assume said first position, engaging said seal,allowing fluid to flow from said pressure source, through said cylinderinlet and said orifice to the interior of said tank, said piston, insaid first position, being effective to block communication from saidtank to said exhaust port and, when said inlet port is depressurized,said piston is acted upon by said pressure in said tank and forced toassume said second position, closing said orifice and allowing a burstof pressurized air from said air tank through said vent port, throughsaid exhaust port into said storage vessel, whereby the relationship ofsaid exhaust port area to said vent port area is effective to maximizethe effect of said burst of pressurized air.
 2. A quick release airdischarge unit as in claim 1 including resilient biasing means disposedbetween said piston and said cylinder adapted to urge said piston intosaid first position.
 3. A quick release air discharge unit as in claim 1in which said piston and valve assembly is removably disposed withinsaid tank and adapted for easy removal therefrom.
 4. A quick release airdischarge unit as in claim 1 in which a plurality of vent ports aredefined in the wall of said cylinder positioned at the lower end thereofand located around the periphery thereof.
 5. A quick release airdischarge unit as in claim 1 including a flange member adapted to beconnected to said piston and valve assembly and wherein said seal issecured between said flange and said cylinder for easy removal andreplacement.
 6. A quick release air discharge unit as in claim 1 inwhich said piston defines at its lower end an inwardly sloping chamferand in which a chamfer is also defined on an internal face of said sealwhereby when said piston engages said seal, a surface of said piston isexposed to the pressurized air in said tank through said vent ports. 7.A quick release air discharge unit as in claim 6 in which the slope ofsaid chamfer on said piston is greater than the slope of said chamfer onsaid seal.
 8. A quick release air discharge unit as in claim 1 in whichsaid pressure tank is ellipsoidal in configuration.
 9. A quick releaseair discharge unit as in claim 1 in which said cylinder is formed ofplastic to prevent corrosion internal to the cylinder.